A variable geometry turbocharger (VGT) vane controller can be used to provide sufficient boost to provide the fresh air flow needed to prevent high levels of particulate matter (PM) emissions, and to provide sufficient exhaust manifold pressure to provide the exhaust gas recirculation (EGR) flow needed to prevent high levels of nitrogen oxides (NOx) emissions. It may be desirable to improve engine efficiency by minimizing pumping losses, so the VGT vanes can be adjusted to provide just enough pressure and flow without causing excessive throttling at the air throttle or EGR valve.
Traditional engine controllers use proportional-integral-derivative (PID) controls to calculate a desired position for the variable geometry turbocharger (VGT) vanes, in addition to a second PID position controller which regulates the pulse width modulated (PWM) duty cycle to the actuator motor. This can require a lot of protections to be built into the controls to prevent compressor surge, turbo over-speed, high exhaust manifold pressures, valve float due to engine delta pressure, and closing the VGT vanes beyond the peak power point. All of these protections and limits can require a significant amount of calibration effort.
It would be desirable to integrate a plurality of these constraints and protections into a control system or method that determines a desired exhaust manifold pressure, and determines a VGT vane position that achieves the desired exhaust manifold pressure using a feed forward model.